Finite Element Methods against Limit Equilibrium Approaches for Slope Stability Analysis

A number of powerful numerical models, including limit equilibrium and finite element (FE) methods, have been developed for slope stability analysis in recent decades. The limit equilibrium method contains several limitations, yet is considered the most common approach. However, the advancement of technology has increased the use of the finite element method as it embraces a wider range of features. The limit equilibrium software, SLOPE/W, and the FE program PLAXIS are two common software programs currently employed in geotechnical engineering. Slope analysis using the limit equilibrium method involves a series of slip surfaces dividing ground into vertical slices, and using the static equilibrium equations to calculate the factor of safety (FOS) and stresses for each slice. PLAXIS requires the input of soil properties and elastic-plastic parameters of elements. In this study the properties of a heterogeneous slope, consisting of general fill embankment over soft, slightly overconsolidated clay is implemented in each program. The FOS of slopes is determined for subsequent design requirements, and results are analysed and comparisons are conducted. The effect of Youngâs modulus on the FOS is also discussed. Recommendations are provided based on the results and previously published findings. The contribution of this paper is beneficial to geotechnical engineers, as it discusses the suitability and limitations of each method and assesses reliability of model outputs for slope stability analyses